Twitter announced its list of the Top 10 most powerful tweets of the year on Tuesday, and TODAY show anchor Ann Curry’s 50-character message imploring the Air Force to allow physicians to land in Haiti to administer aid to the injured and dying came in No. 1.

KABUL, Afghanistan — At least 100 relief workers in Afghanistan have been killed so far this year, far more than in any previous year, prompting a debate within humanitarian organizations about whether American military strategy is putting them and the Afghans they serve at unnecessary risk.

The recent report on AIDS in South Africa, where Doctors Without Borders has been providing AIDS treatment for 10 years, lays out stark policy choices its government must make in order to reduce AIDS deaths and avert millions of infections in the next 20 years.

Guest blog by David M. Olson, MD, Medical Advisor, Médecins Sans Frontières/Doctors Without Borders (MSF), New York, NY, USA. This week I have been called back to Haiti because of the cholera epidemic that first hit in late October and which continues to have a devastating effect. At the time of writing this post, more than 1,100 people have died and over 18,000 hospitalizations due to cholera have been reported throughout the country.

With less than a week to go before presidential elections in Haiti, aid agencies are struggling to contain a growing cholera epidemic on the island. At least 1,250 Haitians have now died of cholera and thousands more are infected with the disease, which is spreading through the capital Port-au-Prince and other parts of the country.

Barely hidden beneath the surface of Pakistan's worst flooding in living memory were the geopolitical stakes shaping both the justifications for official Western assistance and how aid was delivered to victims of the disaster. The perverse result may be a further restricting of the ability of humanitarian aid workers to assist the Pakistani population in the most volatile areas of the country.